The trash had piled up on parkland located outside Orchard Towers at 2777 Kipling Ave., south of Steeles Avenue West. Much of it has been sitting in a field next to the Humber River.
A city official told CBC News that the mess included household waste, diapers and strollers left in trees, after they didn't make it to the ground after being thrown from above.
City inspectors had warned the landlord to clean up the garbage at the end of April.
When that didn't happen, the city stepped in.
Crews have been working on the clean-up for a week and it's not expected to be completed for another few days. Sixteen bins of garbage have been hauled away so far.
The total clean-up is expected to cost some $25,000. The property owner will be billed.
The city says it has been dealing with complaints about similar issues at the same building, as far back as 2001.
Orchard Towers did not answer the phone when CBC News called its office, nor did it return a message left by a reporter.
Watch the video to see a full report from the CBC's Natalie Kalata.